Sankaran Neeraja
History of Science, Technology & Medicine Underwood International College, Yonsei University, 50 Yonsei-Ro, Seodaemun-Gu, Seoul 120-749, Republic of Korea.
Stud Hist Philos Biol Biomed Sci. 2012 Dec;43(4):741-50. doi: 10.1016/j.shpsc.2012.06.002. Epub 2012 Aug 9.
Scientific theories about the origin-of-life theories have historically been characterized by the chicken-and-egg problem of which essential aspect of life was the first to appear, replication or self-sustenance. By the 1950s the question was cast in molecular terms and DNA and proteins had come to represent the carriers of the two functions. Meanwhile, RNA, the other nucleic acid, had played a capricious role in origin theories. Because it contained building blocks very similar to DNA, biologists recognized early that RNA could store information in its linear sequences. With the discovery in the 1980s that RNA molecules were capable of biological catalysis, a function hitherto ascribed to proteins alone, RNA took on the role of the single entity that could act as both chicken and egg. Within a few years of the discovery of these catalytic RNAs (ribozymes) scientists had formulated an RNA World hypothesis that posited an early phase in the evolution of life where all key functions were performed by RNA molecules. This paper traces the history the role of RNA in origin-of-life theories with a focus on how the discovery of ribozymes influenced the discourse.
关于生命起源理论的科学理论，在历史上一直存在着“先有鸡还是先有蛋”的问题，即生命的哪个基本方面最先出现，是复制还是自我维持。到了20世纪50年代，这个问题从分子层面提出，DNA和蛋白质开始代表这两种功能的载体。与此同时，另一种核酸RNA在起源理论中扮演了反复无常的角色。由于它包含与DNA非常相似的组成部分，生物学家很早就认识到RNA可以在其线性序列中存储信息。随着20世纪80年代发现RNA分子能够进行生物催化（这一功能此前仅归因于蛋白质），RNA承担了既能扮演“鸡”又能扮演“蛋”的单一实体的角色。在发现这些催化RNA（核酶）后的几年内，科学家们提出了RNA世界假说，该假说假定生命进化的早期阶段所有关键功能都由RNA分子执行。本文追溯了RNA在生命起源理论中的作用的历史，重点关注核酶的发现如何影响了相关论述。
